1. Field of Invention
This invention relates to the preparation of 3,3-bis(chloromethyl) oxetane and is particularly related to an improved process for the preparation of this compound in high yield, and in high degree of purity.
2. The Prior Art
It is well recognized in the prior art that 3,3-bis(chloromethyl) oxetane may be polymerized to commercially valuable polymers which can be formed into films or molded into various shaped objects. Several methods have heretofore been disclosed for the preparation of this monomer, i.e., 3,3-bis(chloromethyl) oxetane. According to one method which is described in U.S. Pat. No. 2,794,027, an aqueous dispersion of pentaerythritol trichloromonohydrin or an ester thereof, is contacted with an inorganic base such as an alkali metal hydroxide at a temperature of 90.degree. to 170.degree. c., and the resulting 3,3-bis(chloromethyl) oxetane is removed from the reaction mixture by distillation.
Another method of preparation of this monomer is described by F. J. Connelly in an article entitled "Case History of Polymer Process Development," published in Chem. Eng. Prog. Symosium Series, No. 49, vol. 60, pp. 49-57. The method described in this article contemplates a three step reaction process in which pentaerythritol is first acetylated with acetic acid to prepare pentaerythritol tetraacetate, followed by the hydrochlorination of said pentaerythritol tetraacetate to pentaerythritol trichloroacetate and, finally, reacting said pentaerythritol trichloroacetate with sodium hydroxide to produce 3,3-bis(chloromethyl) oxetane by a so-called "ring closure" reaction.
The process described in the foregoing article suffers from disadvantages in that low yields and/or low degrees of purity of 3,3-bis(chloromethyl) oxetane product are produced which product is not particularly well suited as polymerization grade monomer. In addition, and in some instances, the production of 3,3-bis(chloromethyl) oxetane, or its precursors, is accompanied by the production of considerable amounts of undersirable by-products which extremely complicate the production and recovery of the desired monomer, hence making it economically unfeasible to operate the process on a commercial scale. There is thus a need for an efficient, commercially practicable method of making 3,3-bis (chloromethyl) oxetane in substantial yield and in high degree of purity.